1. Field of the Invention
The present invention relates generally to cleansing compositions, and more particularly to cleansing compositions that are prepared in tablet form for use.
2. Description of the Prior Art
Cleanser compositions, and in particular those compositions having utility for hard surface cleaning applications, have utilized oxidizing agents and bleaching agents in concert to remove visible stains, while at the same time providing the capability for the removal of scale or plaque buildup on the surfaces. Thus, a variety of cleansing compositions are known and have been prepared either with abrasive materials for use as scouring cleansers or alone for purpose of mild surface cleaning applications such as passive dispersion in a liquid medium such as water, for soaking applications, such as the cleaning of dentures. All of these compositions have employed a variety of sulfate salts, such as bisulfates, monopersulfates, and sulfates as detergents, oxidizers and the like, and have also utilized alkali metal and alkaline earth metal halides as bleaches. Such compositions have also included perborate, carbonate and phosphate salts in varying amounts, to provide effervescence and activation. Representative cleansing compositions covering these various applications are set forth in U.S. Pat. No. 3,337,466 to Puetzer et al., U.S. Pat. No. 3,458,446 to Diaz, U.S. Pat. No. 3,558,497 to Lawes, U.S. Pat. No. 3,704,227 to Hill, and Applicant's copending applications, Ser. Nos. 251,030 and 297,892, all of which are incorporated herein by reference.
In the instance where the cleansing compositions mentioned above contain one or more perborate salts, and the compositions are prepared into tablets by compression, the compositions have presented certain drawbacks in that they are difficult to compress, and the resulting tablets lack mechanical strength. These problems are owing primarily to physical properties of the perborate salts employed. In particular, anhydrous sodium perborate, which has been utilized in the compositions in my copending applications, is commercially available as a fluffy powder having a low specific weight and density and therefore resistant to compaction and agglomeration. To a lesser extent, this same difficulty is experienced with another perborate salt additive, sodium perborate monohydrate.
Prior attempts to remedy these deficiencies have focused upon the addition of greater amounts of standard tableting aids such as talc, sodium benzoate, and the like. The addition of greater amounts of these ingredients, however, while remedying the difficulties of initial processing and tablet formation, carry with them certain other drawbacks, namely that the formed tablets exhibit retarded action in use, that renders them less commercially desirable. In particular, the increased amounts of tableting aids tend to prolong the disintegration time of the tablet, with the result that the activity of the tablet is delayed and in some instances slightly suppressed, and therefore less attractive to potential consumers.
A process is disclosed in U.S. Pat. No. 4,115,519 to Brichard et al., for the manufacture of sodium perborate monohydrate, that purportedly results in the preparation of granules of the monohydrate possessing the desired particle size, specific weight, abrasion resistance and flowability sought for use in connection with the compaction of dental cleanser tablets. The technique disclosed by the patent, however, is complex and costly, and requires specialized apparatus to conduct a fluidized bed particle formation in contact with hydrogen peroxide. The patentees refer to prior art processes for the formation of the monohydrate salt, and indicate that those processes, as well, are complex and expensive, and frequently yield particles that are unsuitable for the present applications.
U.S. Pat. No. 3,340,152, to Hotko, discloses that polyfluorocarbons may be utilized in the manufacture of tablets, as lubricants, and in amounts by weight of the tableting composition, ranging from about 1% to about 15% by weight, to supplant such known lubricants as magnesium stearate, sodium lauryl sulfate, polyethylene glycols and the like. Hotko suggests that the fluoropolymer may be added directly to the tableting mixture, in its capacity and amount as a lubricant, and purportedly has a favorable effect on the tablet-forming process. There is no disclosure in Hotko that the fluoropolymers would serve as agglomeration or compaction aids, to facilitate the preparation of granulated materials of increased and improved specific weight.
A need therefore exists for the preparation and employment of a granulated perborate salt that is easily and efficiently compressed in combination with the remaining ingredients of cleansing compositions, to enable the compositions to be formed into cleanser tablets that exhibit mechanical stability without reduced activity.